Higher testosterone levels can boost the male sex drive, and exercise has been shown to raise testosterone levels. But new research suggests too much working out can have a negative effect on the male libido. When scientists at the University of North Carolina in Chapel Hill surveyed men about their workout routines and sex lives, they found men who engaged in frequent and strenuous exercise were more likely to have low libidos. The study included three separate questionnaires: one featured intimate questions about the respondents sex life, another featured inquiries about the respondent's weekly workout routine, and a third featured general health and wellness questions.